Analyses Given by Different Methods

Comparative analyses of the various methods are presented in Table 11. From the data available the gas-evolution method is generally the most precise and least subject to error once the operator has developed the manipulative skill and experience. It tends to yield the highest azide contents, particularly for lead azide. Loss of hydrazoic acid is minimal, and provisions are made for collecting any carbon dioxide generated by oxidation of the phlegmatizing agent. The 2-g 

Material Nitrogen evolution No distillation Distillation Argentometric 

The titration of excess standard ceric ammonium nitrate solution after addition of azide either as a slurry, solution, or as distilled hydrazoic acid gives precise and accurate results. The ferroin endpoint is sharp and virtually instantaneous. Loss of hydrazoic acid in the distillation is apparently nil, and the reaction of hydrazoic acid with ceric ion is extremely rapid. 

In Table II the results are presented of investigations conducted in the United Kingdom [2] and the United States [15. 21] to compare the data for azide ion content of various commercial azides as determined by the above four methods. Different samples were used for each of the investigations, and thus it is not possible to make direct comparison with respect to the reproducibility of data from investigation to investigation. Despite the precise results, manipulation of azides in acid solution is always subject to error through possible loss of hydrazoic acid it is preferable to work in neutral solution. 

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